Autotransformer



A. D. RiCC iA.

7 AUTO TRANSFORMER. APPLICATION FILED DEC.2, 192I.

1,426,775, 7 Patented Aug. 22, 1922.

UNITED ST TES ANGELO DELLA RICCIA, OF BRUSSELS, BELGIUM.

AUTOTRANSFORMER.

Specification of Letters Patent. Patented Aug. 22,1922.

Application filed December 2, 1921 Serial No. 519,560.

To all whom it may concern.-

Be it known that I, ANonLo DELLA Broom, residing at Brussels, Belgium, 253 Chausse dAlsemberg, have invented certain new and useful Improvements in Autotransformers, of which the following is a specification.

In various applications of single-phase and polyphase currents, auto-transformers are employed for regulating between 0 and the working tension, the voltage used upon motors or like apparatus. Fig. 1 of theac-- coinpanying drawings shows a diagram of the known arrangement of an auto-transformer of this kind, wherein T is the autotransformer, R the motor or like device supplied and 2 the movable contact member cooperating with the contact pieces from 1 to 4. a

The invention is applicable in the case in which the motors or like devices to be supplied are disposed in pairs,'and relates to a particular arrangement wherein the teching partly as a continuous current shuntand as secondary, and partly as a primary circuit. U a y I hereby propose to increase to the maximum the portions of the winding which are intended for use as shunt and secondary and to reduce to a minimum'the portions of the winding to be used as primary, thereby reducing the mean value of all the currents employed, with a consequent increase in efiiciency.

In theaccompanying drawings, Fig. 1 shows the known arrangement of an autotransformer. Fig. 2 and the following fig ures set forth diagrams of dispositions according to this invention. Figs. 2 and 2 show for two positions of the movable contact an arrangement for single-phase current with twogroups of apparatus to be supplied. 3 shows the arrangement for In Figs. 2 and 2, T is the auto-trans former, R, R are the two apparatus or groups'of apparatus onv the supply circuit, 1 and 4 are the end contact pieces of the autotransformer, 2 and 3 are the contact members movable upon the contact pieces from 1 to 4. Supposing that the contact members 2 and 3 are symmetrically disposed with ref erence to the middle contact piece m. and are obliged to move through equal distances in the contrary sense, the auto-transformer will be symmetrically loaded. WVhen the contact members 2 and 3 coincide with the middle contact piece on, B1 and R, will be connected in series, and the transformer will operate without load. WVhen theicontact member 2 is upon the contact piece 4 and the contact member 8 is upon the contact piece 1, R, and R, will be connected in parallel and will receive the full voltage, and the auto-trans former will also operate without load.

If e is the standard voltage of the work.- ing circuit, 2' the power-current taken by each group ofapparatus R, R 7' the total resistance of the winding of the atuo-transformer if it be supposed that all wattless current is neglected and if the voltage supplied to the two groups R, R is I varied in a uniform manner, the mean power furnished .bythe auto transformer is: i 1

s ea in the case of Fig. 1. J, 62' in the case of Figs. 2 and 2. I and the los n heat is: l

% ri in the case. of Fig. 1 Q, m' in the case of Figs. 2 and2;

A like arrangement may be used forpolyphase currents.

Fig. 3 shows by way of example an arrangement for three-phase current with the auto-transformer T mounted in delta connection and supplying two three-phase'motors M M also in delta connection. A B, C, and D E F are respectively the three windings of each of the motors which are respectively supplied by the six correspond ing sections A B C D E F of the autotransformer. If the movable contact members 2 and 3, 5 and 6, 8 and 9 are caused to move at each side of the triangle by equal amounts and in the contrary sense, the ar- I rangement will provide in the case of each phase, the same operating conditions and advantages as above set forth for the singlephase circuit in Figs. 2 and2. It must be observed that. the two motors M M should possess three phases which are entirely separate in 2 r mcnt. For the apparatus with sta conn ction. the threephases should not possess a common fixed neutral point.

To obtain the above-described displace ment of the movable contacts for each phase, the apparatus may he provided with a device such as the. controller shown by way of example in Fig. i. The said controller consists of a double set of COilttLCt pieces disposed in contrary sense and connected in pairs with the correspondimg points oi the auto-transformer windings and six sectors cc, of), co, dd, cc, each ot which is respectively connected with one end of the six corresponding windings oi the motors, the. other ends of the said windings being respectively connected with one of the contact pieces correspondin to "the main terminals of the auto-trans'ltormer st, T, 1, 7, t). The amparatus employs A B C D E F spaced at and Inechani. cally connected together, in order to make contact siu'cessively between the various contact pieces and the sectors. The width of the slides A B C D E F cooperating with the said contact pieces should be made smaller than the space between the contact pieces to prevent short circuitingoi the sections 0". the autotranslormer.

It is obvious that the contact g'iiecera sectors and slides corresponding to the windings in the supply circuit, may, insteat of being disposed upon a single disc (or cylinder) as shown diagrammatically in Fig. l, be divided into two,-thrcc or six. superposed rows and placed in an oil bull's .li nown devices may be added thereto for obtaining a quick break oi the circuit and the stoppage oi the slides at determined points.

The operation of a control device may, it desired, be elfected by a servomotor and the latter can be regulated by one or more relays if necessary.

Claims:

L-An auto-transformer for the supply 0! two syn:metrically disposed secondary circuits, com 'irising' tor each secoznlary circuit a stationary terminal connected in the circnitat the correspondinn end of the trans former winding and a terminal movable along the said winding the t vo movable terminals being symmetrically disposed, and means for moving the same by equal amounts and in contrary sense upon the whole length of the wind 2.A.n au"to-trans" A ic F lll} )l.)l' 'y' oi two sylnmetrical'ly disposed :ondary circuits for each phase C()1'i1])ll5lll l'or each secondary circuit a stationary terminal cl|I1- nectcd in the circuit at one end oi the transit'mrmor winding correspondii'ig to the plltlf-itl of the said circuit and a terminal which is movable along the said winding, the two movable terminals ot the two sccmida'iy circuits ot a given phase being symmetr-ically disposed on the corresl'iondino; winding 01' the transformer, and means tor moving the same by equal amounts and in contrary sense upon the whole length 0' the said winding, this being ettected siniultancously and in like manner For each of the phases.

lk-Ill. con'ibimition with an autotrax'isformer :tor the supply 01 two synimetrirally disposed secondary circuits for each phase and employing for each sectmdaiy circuit a stationary term mal coni'iccted in the circuit at oneend ot' the corresponding; trans'tormer winding and a terminal movable along the said winding, a controller for displacing the movable terminals coinprising; two so -1 of contact pieces disposed in ccntrarv sense and connected in pairs to the di'tlcrcnt points oi the (.OII'OSl'MHlKllHQ' windings ot the transformer, sectors correspondingto the secondary windings to he s'tugplied, and contact slides movableupon the said contact pieces and sectors lor connecting two separate secondary circuits siniiiltoncously to two separate pOl'lLlUlii-J of a given secondary winding, this being carried out for each phase.

In testimony whereof l a tlix my signature.

ANGELO DELLA RICCIA. 

